1. Field of the Invention
The invention generally relates to a movement assessment apparatus. More particularly, the invention relates to a movement assessment apparatus configured to provide biofeedback to a user regarding one or more bodily movements executed by the user, and a method for providing biofeedback using the same.
2. Background and Description of Related Art
Parkinson's disease (PD) is one of a number of neuromuscular degenerative diseases which can lead to impaired movement or movement disorders. PD is caused by cell death and loss of dopaminergic neurons in the substantia nigra region of the brain. This results in a significant reduction of the production of dopamine, an essential neurotransmitter which controls motor function. The loss of dopamine production due to PD may result in a variety of symptoms including movement problems such as slowed or shortened gait and stride, stiffness, diminished or loss of arm swing on walking, tripping, falling, tremoring, bradykinesia, rigidity and other effects.
PD is often distinguished by similar disorders, for example essential tremor, due to the fact that PD initially manifests symptoms unilaterally, or on one side of the body first. This unilateral characteristic of movement symptoms leads to unequal movements between one side of the body and the other, creating further difficulties with mobility. As PD progresses, these movement problems increase, often to the point where mobility is significantly compromised and quality of life of the patient decreased. Although there are a number of effective pharmacological treatments which address decreasing dopamine levels and increasing mobility, often the differences in one side of the body compared to the other are not directly addressed.
There is a growing body of thought that argues for earlier intervention in the changes in mobility prior to significant loss of function. There is a need for devices which are designed to address earlier symptoms which eventually lead to more significant mobility issues. An early symptom of PD which eventually advances to mobility problems is limited and asymmetric arm swing.
Movement changes due to the effects of PD and loss of dopamine are often noticed by other people, such as family members, before the patient is aware of the movement deficiency. For movements such as gait, stride and arm swing which are learned in early childhood, one relies on muscle memory unless there is some indicator that there is a change in movement. In a healthy individual, there are biofeedback mechanisms which provide such indicators. In the PD patient, the loss of dopamine neurotransmitters likely compromises both the outward signal from the brain to the muscular-skeletal system as well as the return signal indicating the movement has been executed as expected. This breakdown leads to a lack of awareness in the PD patient of the loss of movement speed, amplitude and symmetry. There results in the patient a kinesthetic misperception which must be addressed for normal mobility to be maintained as long as possible.
Until recently it was thought that the generation of new neurons was confined to the earliest stages of life, or in the embryo. New studies are showing that all cortical areas of the brain, even in adults, can exhibit surprising neuroplasticity, or modulations in function and synaptic activity with time and repetitive stimulus. There is also evidence that neurogenesis is possible. Studies show increases in volume of specific cortical areas after various stimuli (see e.g., B. Johansson, Brain Plasticity and Stroke Rehabilitation: The Willis Lecture, Stroke Journal of the American Heart Association 2000; 31:223-230). Neuroplasticity has been credited for the recovery of lost function when the brain compensates for damaged or impaired regions through repetitive retraining of the body. These new neuro-pathways are created by repetitive stimulus. To achieve corrected repetitive motion stimulation requires some sensory bio-feedback system to allow the patient to feel by an alternative method, the corrected motion. This may allow the patient to bypass the damaged biofeedback creating the misperception of proper movement.
A good example of this approach is the use of speech therapy to overcome the PD symptom of soft and poorly inflected speech using audio recording and the physical feeling of the level of energy of speech correlated to volume. This compensates for the loss of personal auditory feedback, which does not indicate a problem to the patient. Further examples of alternative feedback and neuroplastic approaches are the use of singing to enhance speech and dancing to enhance motor abilities in PD patients, by accessing broader parts of the brain utilized by alternative but related activities.
Diminished or lack of arm swing in PD patients is often manifested unilaterally, with one arm swinging normally, or with an increased arc and greater range of motion than the other arm, which is often stiff and diminished in motion or still. This asymmetric motion of the arms while walking contributes to poor balance and a decline in normal gait and stride (see e.g., Lewek et al., Arm swing magnitude and asymmetry during gait in the early stages of Parkinson's disease, Gait & Posture 31 (2010) 256-260). The PD patient has the ability to consciously move the arm with specific intent, but there is no automatic rhythmic swing on walking. When intentionally moving the arm, the patient is using visual feedback to override the damaged natural impulse. This visual signal is limited to the forward swing of the arm as the back swing cannot be seen. Also, the amplitude of the arc of the swing may or may not match the other arm.
Therefore, what is needed is a device for providing feedback that can be used for training or retraining the body and brain to recognize and correct for abnormal or asymmetric arm swing in PD patients or others having a similar problem. Moreover, what is needed is a simple arm swing device that is capable of being effectively used to retrain individuals having diminished arm swing. Furthermore, an effective sensory feedback device is needed that can measure and indicate the range, speed and flow of the diminished arm as compared to the looser arm to obtain a normal pattern of gait, stride and balance. In addition, what is needed is a device that can measure, signal and feed back to the walker the speed, range, fluidity and any other indicators, in comparison to the other arm, or in comparison to a targeted normal arm swing.